The THUNDERCATS meet the BERBILS, a group of robot teddy bear-like creatures from the planet RO-BEAR. Their leader, RO-BER-BILL captures LION-0 and SNARF but the THUNDERCATS soon learn that the BERBILS are "good guys" and they help them defeat their natural enemies, the GIANTORS and the TROLLOGS. Making matters worse, MUMM-RA transforms himself into a swarm of locusts and he descends upon the BERBILS' crops. LION-0 and the mighty sword defeat him. In triumph, the BERBILS agree to help the THUNDERCATS build the Cats' Lair.

Lion-O learns the value of friendship and the importance of cooperation. When groups have interests in common, joining together and sharing their talents and resources can best serve their welfare.

Positive peer group relations are important for children. They provide an opportunity to interact socially, express emotions, develop a self-image, and solve interpersonal problems. Friendship expectations differ in children according to age. Younger children choose friends on the basis of common activities and propinquity. Older children choose them more on the basis of central personality characteristics and include elements of self-disclosure, empathy, and understanding in their choices. In general, friendships based on stable mutual interests are the most intimate and enduring.